I just want to put in a plug for talking to instructors. I am fortunate to have occasions to know many colleagues across campus. And I know the majority of them really want to interact with their students, but often bemoan the fact that no one comes to their office hours. So here's hoping you take pity on us lonely profs and come by and talk to us sometime.

I believe that keeping a dialogue with professors is very important. When I first arrived here at Western and took some of the very large lecture classes, I felt like just another face in the crowd -- never talked in class, never introduced myself to professors etc. But once I've gotten higher up in my education and class sizes have decreased, it feels like a much more intimate environment. I make a point to always participate in class, go to office hours if I need help, or sometimes just to bounce ideas around.
Although I do believe that many professors don't seem very accessible to students. When going over course syllabi, while the office hours are mentioned, most professors that I have always inform the class that the best way to reach them is via e-mail. Perhaps if professors explicitely mention that they welcome students to come by during office hours (even just to chat), it would make students feel more comfortable doing so.